Assertion (A): During urination, urine is prevented from flowing reverse into the ureter.
Reason (R): Urethral sphincters relax during urination.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. Both (A) and (R) are false.